Remove jailbreak from PS3...?

You can upgrade from 3.55 to any firmware above 3.55. If you have 3.55 CFW on the PS3 and you connect to PSN and go to settings and update, it will tell you there is a 3.61 update available and ask you if you want to download 3.61 and it will install the latest firmware, no matter which firmware you are on right now.